Group A streptococcus (“GAS”, S. pyogenes) is a frequent human pathogen, estimated to be present in between 5-15% of normal individuals without signs of disease. When host defences are compromised, or when the organism is able to exert its virulence, or when it is introduced to vulnerable tissues or hosts, however, an acute infection occurs. Related diseases include puerperal fever, scarlet fever, erysipelas, pharyngitis, impetigo, necrotising fasciitis, myositis and streptococcal toxic shock syndrome.
GAS is a gram positive, non-sporeforming coccus shaped bacteria that typically occurs in chains or in pairs of cells. Although S. pyogenes may be treated using antibiotics, a prophylactic vaccine to prevent the onset of disease is desired. Efforts to develop such a vaccine have been ongoing for many decades. While various GAS vaccine approaches have been suggested and some approaches are currently in clinical trials, to date, there are no GAS vaccines available to the public.
It is an object of the invention to provide further and improved compositions for providing immunity against GAS disease and/or infection. The compositions preferably include GAS 40, a GAS virulence factor identified by Applicants, which is particularly suitable for use in vaccines. In addition, the compositions are based on a combination of two or more (e.g. three or more) GAS antigens.